Original Mason Johnston Classification
Classification Definition Clinical Characteristics Treatment Type I Nondisplaced or mildly displaced fractures of the radial head or neck No mechanical block but may have decreased pronation and supination secondary to acute pain and/or swelling Requires early mobilization without cast treatment to avoid elbow and forearm contractures Type II Displaced (>2 mm) fractures of the head or neck (angulated) May have incongruity at the fracture site and mechanical blockage to movement. Normally encompasses more than a marginal lip of the radial head. Lack severe comminution. Usually require open reduction and internal fixation (ORIF) but may benefit from excision in select circumstances such as the elderly. If radial neck comminution is present, then consideration of bone grafting is warranted. During the ORIF procedure, care needs to be given to avoiding the posterior lateral corner to avoid posterior lateral elbow instability. Type III Severely comminuted fracture of the radial head and neck Associated with adjacent injuries such as TFCC tears, IOL tears of the forearm, or elbow dislocations (usually posterior) with or without coronoid fractures. Need to be excised for restoration of forearm movement.
Ref: Hotchkiss R. Longitudinal instability of the forearm. From the 67th annual meeting of the American Academy of Orthopaedic Surgeons (ASSH); March 15-19, 2000; Orlando, Fla.
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